OSPF LSA - the BEST explanation of the Types of OSPF LSAs

[@PracticalNetworking]

📌 *More free preview lessons from the Practical OSPF course:* pracnet.net/ospf 📌 *Want even more? Check out the full course:* pracnet.net/ospfcourse 📌 *CCNA Resources:* pracnet.net/ccna 📌 *Learn Networking:* pracnet.net/nf 📌 *Learn & Practice Subnetting:* subnetipv4.com

[@MahekThaker]

Great, Deep and Simple explanation,l👌

[@JaimeTV-w9j]

best ospf lessons! thank you

[@amrindersingh8634]

Thanks alot for this understanding session sir it's so awesome..... thanks alot sir

[@saidsabar3184]

simply amazing

[@manoj121979]

Excelent explanation about LSA

[@genesistwilight]

Thank you very much, such an amazing explanation

[@adk-e2s]

thanks you

[@ciscogenius8795]

great explanation

[@BasitAli-wy2sq]

Great explanation ...

[@Kaushik846]

nice explanation

[@MuhammadHassan-wv1ns]

awesome thanks for explaining

[@Alfalin0]

Thank's a lot for your time man! your are really helpful!

[@laminceesay1435]

This is a great lesson, Thank you.

[@arii4369]

Thanks for the explanation it was really helpful!

[@weedlax6938]

Good explanation!

[@Apnakitchen.cuisine]

So helpfull

[@asish4ever]

Thank you !

[@rum3er0]

great clarification!

[@哈哈投美股]

Amazing! Very good one!

[@mahendrakumarsahu4395]

Marvelous ❤❤❤ Brother

[@sayan.rahman]

The content is o rich. I watched the video and helped me a great deal. thanks you are awesome

[@Just-Browsing-123]

The diagram you made to help explain this is excellent!

[@jalalalzamili4486]

Well done

[@MT4_Trade_Manager_EA]

Thanks so much!

[@assohonarvar4819]

Thank you

[@PracticalNetworking]

You're welcome.

[@PoteRomo]

Dude, you are one of a kind, man. I mean, YOU EXPLAINED IT AMAZING!

[@PracticalNetworking]

Glad it helped =)

[@James67851]

You've mad something quite confusing very understandable. Thank you.

[@PracticalNetworking]

You're very welcome, James.

[@avelinojrrealingo5703]

Mind Blown!!! its like a clog in my brain has melted due to this OSPF LSA types

[@PracticalNetworking]

Fantastic! Glad this video helped !

[@GokhanDoymaz-oi7lx]

Perfect explained LSA Types 1,2,3,4,5

[@PracticalNetworking]

Thank you, Gokhan =)

[@yasaralzakout7691]

Excellent work and clear explanation. Thank you.🤓

[@PracticalNetworking]

Thank you so much for supporting the channel, Yasa =) I'm thrilled to hear you enjoyed this content.

[@samueltetteh7133]

Great presentation. You simplified every thing .thanks

[@PracticalNetworking]

You're welcome, Samuel !

[@Arvindkumar-vs6mo]

Watching OSPF topics on your channel. One of the Best teacher. You are awesome in conveying the information with pictorial form.

[@mobcer]

finally an explanation that stick to my mind. tnx

[@PracticalNetworking]

Awesome, glad this helped =)

[@TheKhidki]

Saying Thank you is a very least. I really have cleared many doubts through your content.

[@Mr.Acharyya]

You made a magic in 14 Minute....Great Man

[@DhrubRajGiri01]

Love it, short summary of lsa

[@devanandjha5284]

Ed ..Fabulous.. you are my favorite trainer along with jeremy it's lab

[@PracticalNetworking]

Thank you, Devanand =). Cheers !

[@ahmadsalem7222]

Just amazin'!

[@PracticalNetworking]

;)

[@aniswlidi2012]

Greate explanation about the LSAs. Thanks

[@anilkainikara]

Amazing content. The slide designs are appealing to the eyes. And your exploitation is good.

[@ciscobatais2]

AMAZING ❤

[@WDiamhere]

you awsome man .

[@amirniko8014]

thank you!!

[@s_t_8_l_e_s_s]

seriously appreciate your videos, wish I had found you before I payed for other courses...

[@s_t_8_l_e_s_s]

Only a few days away from my CCNA, and your videos have helped explain some topics I was murky on after jeremy & david B's courses. You dont have a Security+ course do you?

[@dc4life_956]

WOW. Best content I've run across. Greatly appreciate your style.

[@fabianravasila6802]

Incredibly well explained. Ty!

[@shahadatanwar4109]

Thanks for easy explanation

[@PracticalNetworking]

You're welcome !

[@kingafadll2006]

I want to say thank you, I am bluffed by how you have explained that, I have purchased many of CCNA & CCNP courses, but no one has explained it the way you did. Thank you

[@chantellemorehead9390]

A passed my CCNA yesterday!! Thank you for the videos, they really helped

[@PracticalNetworking]

Wohooo! Congratulations Chantelle! Huge achievement =).

[@mehrdadahmadi585]

Absolutely amazing

[@PracticalNetworking]

[@DarkArchery1511]

Thank you very much. I really appreciate your explanation with moving diagrams. I currently prepare myself for an exam and it was really hard for me to imagine how it works just out of the slides. Before this video I didn't even understand where the LSA are all send to.

[@goldisss]

That was really the BEST explanation. Thank you.

[@rickwiers1905]

This is the best video I have seen about LSA's in a simple understandable way!

[@adedejiemmanuel1]

Great explanation.

[@PracticalNetworking]

Thank you, Azza.

[@idowuaina7674]

Your videos are simply the best I have come across. Rich in content and details

[@PracticalNetworking]

Thank you for the kind note, Idowu. Glad you have enjoyed this content.

[@PKJamal-b5q]

excellent presentation. Thanks!

[@narinderpal61]

Brill Sir just Brilllllllllllllllllllllllll

[@mikemoman]

Brilliant. You explain these topics so well. Thank you.

[@ShreyA-ms3pe]

Wow just wow. These videos helped me to get into one of the MAMAA companies. Thanks to you. Please please make similar videos on BGP.

[@PracticalNetworking]

Whoa that's awesome! Congratulations! Which one? BGP is on my list, at some point I'd love to get to it. But no imminent plans.

[@weberleone4295]

Excellent explanation!

[@PracticalNetworking]

Glad you enjoyed it, Weber =)

[@eternalblue4660]

Thanks a ton, very succinct explanation :)

[@aler3119]

Best explanation I have come across so far! Thanks for the great work.

[@PracticalNetworking]

You're very welcome, Ale. Cheers.

[@randyyihsienhan]

Another great tutorial. Wish to learn advanced BGP and Eigrp from you.

[@PracticalNetworking]

Noted about BGP, Randy. As for EIGRP, I wrote three EIGRP articles you might enjoy: EIGRP Explained : www.practicalnetworking.net/stand-alone/eigrp-terminology/ EIGRP Metric : www.practicalnetworking.net/stand-alone/eigrp-metric/ EIGRP Feasibility Condition: www.practicalnetworking.net/stand-alone/eigrp-feasibility-condition/

[@Noah-xn5th]

Yes, this is indeed the best explanation.

[@u82zar]

Sorry to be that person but there are actually 11 types of LSAs (OSPF). LSA Type 1 Router LSA LSA Type 2 Network LSA LSA Type 3 or 4 Summary LSA & ASBR LSA LSA Type 5 Autonomous System External LSA LSA Type 6 Multicast OSPF LSA Type LSA Type 7 Defined for Not-So-Stubby-Areas LSA Type 8 External Attribute LSA for BGP LSA Type 9,10,11 Opaque LSA RFC 5250 back in 2008 discusses these. Cisco, one, it not the largest, vendor which many people are familiar with, only supported 1-5 for the longest but other vendors supported OSPF LSAs (6-11) well before especially with the advent of Traffic Engineering (10-11 "Opaque" LSAs). Very good explanation on the 5 types you discussed here.

[@PracticalNetworking]

I did say the 5 "main" types of LSAs at the start of this video ;)

[@danielandrade671]

superb!

[@PracticalNetworking]

Hi Daniel, thank you for supporting the channel =) Glad you enjoyed the video!

[@calcen_]

It is helpful as I am currently preparing for CCNA. So I am gonna jump to the Type1 and 2 LSA video of yours:) Thanks a lot

[@tonicshahov8153]

Your explanation of LSA types is trully best, as you promised in description!

[@PracticalNetworking]

Glad you enjoyed it, Tonic. Thank you for the kind words.

[@mikgruff]

Nicely done thank you so much for your time.

[@PracticalNetworking]

You're welcome. Glad you enjoyed it =)

[@sydneym9970]

Good explanation. You might have had a typo on you ASBR. Instead of "Boundary" you used "Border"

[@davidjimeneztech]

Absolutely amazing how you explain this topic

[@PracticalNetworking]

Glad you enjoyed it, David.

[@huyvuquang2041]

I really really appreciate your work. Keep it up please. You helped me so much....

[@PracticalNetworking]

So glad you found these helpful, Huy. Cheers =) If you're willing... Could you do me a favor? Do you mind sharing this video on Linked In, Reddit, Twitter, Facebook, or any other social media you use? As an independent creator, that would be an _enormous_ help, and I would appreciate it _greatly_ .

[@huyvuquang2041]

@@PracticalNetworking Since I use facebook, I will help you share it on this platform :)))

[@PracticalNetworking]

@@huyvuquang2041 Thank you for your support, Huy =)

[@blackbarry45]

gread vid

[@PracticalNetworking]

Thank you =)

[@zakariabouguenara3728]

OSPF's professor

[@PracticalNetworking]

;)

[@wwolfram33]

@ 2:52, if R2 and R3 are then configured with OSPF, would not Hello Packets, DBD, LSR, ... to form adjacency have happen? The forming of the adjacencies must take place with R2 and R3 before L1's can be sent. I can see how LSU/LSAs would be sent upstream from R1, or after adjacencies have already formed. Could you tell me what I am missing? What is the transition from creating full adjacencies between two OSPF routers and when LSA types begin to fully operate. Thanks!

[@PracticalNetworking]

Yes, all that would still happen. I'm simplifying that out in this video to focus on LSAs. But everything else in the series still applies (hello packets, LSU/LSR/LSA/DBD, neighbor adjacency sequence, and so on)

[@Martaftw]

Fcking brilliant explanation. Smthing my lector failed to do so.

[@scottspa74]

Ed, you're a bit of a savant. I will never understand how you can have such a grasp of all of this. Your instruction is fantastic, I will have to review this when I'm not half asleep, but what you share with us is AMAZING.

[@PracticalNetworking]

Thanks for the kind words, Scott =). Yes, definitely let us know what you think when you get back to this video. Cheers !

[@viveknjoy25]

Have a doubt at 11th minute of the video about type 4 LSA, R6 will introduce it to R4 by type 1 LSA, and these will be shared to area 0 via R2 as type 3 LSA, so Routers in R1 will knows about R6 right?

[@mohancpab]

Well explained! do you have deep dive in EIGRP?

[@PracticalNetworking]

I have three articles on my blog that covers most of what most people need to know about EIGRP.

[@khusi2145]

What an explanation ... by the way I'm from India. Could you please tell me the simple definition of a domain ? I'm not getting it.

[@ezawa4]

Many thanks. One question about example with 3 Routers R1,R2,R3 starting approx at 2:30, you mention that there's only 1 LSA type 1 per router (and update if necessary). When R3 emits its LSA type 1, in order for R2 to be aware of R3 update, I guess R1 propagates the update with a LSU (?), is it correct ? i am confused for now, with the propagation mechanism in order for all routers in area 0 to have the same LSDB.

[@PracticalNetworking]

Yes. Correct. After Routers are already neighbors with each other, they just send LSU's with new / updated info when necessary

[@susmitamazumder8390]

Passed the ccna

[@PracticalNetworking]

WOHOOO! Congratulations!

[@hrishabhdivya]

why did the area 0 and area 55 did not knew about router 6 through type 3 summary LSA, assuming R4 to be DR, would Type 3 LSA not have the knowledge to reach R6? that R4 can share with area 0 and then area 55, am missing something?

[@rmmhn]

what would be type of LSA in area 44, when ABR R2 summarizes both Area 0 and Area 55, would it still be LSA 3 or LSA 1 ?

[@PracticalNetworking]

Always LSA3. Every summary of IP networks from another area within OSPF shows up as a Type 3 =).

[@dylanwinslow8585]

Why is R6’s Type 1 LSA / subnet that is sent to R4 not then sent to area 0 / R1 by R2 via a Type 3 LSA (if a type 3 is summarizing all the Type 1&2’s sent within its area) at which point it would know how to reach R6 when trying to get to the external subnet?

[@vanbaole8415]

Hi Ed I don't get why we need type 4 LSA. When router R6 introduced it self in area 44 via type 1 LSA should the ABR router R2 have sent type 3 LSA including subnet 9.9..9.0/24 in the summary into area 0? so every routers how to reach R6.

[@wwolfram33]

@10:56, it is stated that R6 has introduced itself into Area-44 using a Type-1 LSA. I am missing something here. Are we assuming that R4 and R6 are already neighbors? If so, how does this introduction happen?

[@PracticalNetworking]

Yes, they are already neighbors. The implication is that all routers in the same areas have become neighbors because of their Type 1 LSAs. Of course, normally they would be sending hello packets and validating various attributes, but for this video I'm simplifying and saying all routers in the same area are neighbors.

[@wwolfram33]

Thanks! @@PracticalNetworking

[@lokeshreddysura6836]

I have been searching for almost 7 years to know what is the LSA Types differences and their nonsense theory and you nailed it in a shot. Superb. It feels like no instructor knows what exactly LSA's are except you.

[@thamkinkottayil6375]

Gooooood woooooorrrkkkk👏👏

[@PracticalNetworking]

Thank you =)

[@aniswlidi2012]

No sure to understand why there is no TYPE 2 LSAs on the 2 segments between R1and R2, and between R1 and R3 since there is also a DR on each link (this after minute 4). Arent these also multi-access links?

[@exaaltare1170]

So if a ASBR router introduces with Type 1 LSA to area 44. Why doesn't that type 1LSA get summerised within Typer 3LSA together with all of the other type 1 and 2 LSA's? Type 4LSA would seem like a owerhead. Im sure im missing some critical detail, can anyone explain?please

[@PracticalNetworking]

It's not the LSA itself that gets summarized by a Type 3. It's the _content of the LSA_ (in particular, the IP Networks contained in the LSA) that gets summarized by the type 3. Type 3 LSAs do not contain any information about the routers in foreign areas.

[@Vova67ify]

I still don't understand why they created LSA5. They could use LSA1 that ASBR generates anyway to spread external routes. Just put all the external routes that you got via redistribution inside LSA1 and it's done. And you can spread them as normal LSA1. Instead of that they created LSA5 and when they realised that it was unreacheble they also created LSA4. I don't understand. I think I miss something. It looks like for me that they just didn't want to change LSA1. It was simpler to add a couple of more LSAs to handle external routes.

[@НикитаМорозов-я7ы]

Hi! I belive, that you missed one important moment about Type 2 LSAs. When you using Ethernet ports on touter (and nowadays you will mostly use Ethernet) routers by default will treat this links as multiaccess, because they can't know do this link connects directly to another router, or there can be switch in beetwen and potentially multiple routers. So, if you only connect two routers by Ethernet link directly to each other - they will treat this link as multiaccess, chose DR and BDR and will send Type 2 LSAs. You need to explicitly configure this links as p2p.

[@PracticalNetworking]

Correct! That is explained in the Type 1 & Type 2 deep dive video: kzbin.info/www/bejne/Z3eyc55_pKmVecU =)

[@blackbarry45]

4:02 can R2 be a DR ? because it just happened in my GNS3 LAB

[@PracticalNetworking]

Yes! If you're building the topology, any of the routers on the multi access segment could be the DR (R2/R7/R8/R9). Itw ill be whichever router wins the DR election (or is the first to be stood up). Details in the DR video: kzbin.info/www/bejne/g5qWpYGJis-VbZo

[@hampusgotlind2357]

You are such a legend. Makin everything so easy to understand! Thank you =]

[@PracticalNetworking]

You're very welcome, Hampus.

[@gong2094]

❤

[@Alestrix76]

If you say that the internal routers are representative of any number of internal routers, how about the ABRs? I've watched several intros to OSPF and they all use just a single ABR between areas which immediately makes be wonder about redundancy. I mean isn't this one of the main reasons to use a routing protocol, resilience to hardware (link or router) failures?

[@hait7393]

Thank you for your great work, just one remark regarding type 4/5 LSA, you mentioned that router 6 (which is an ASBR) introduced itself to router 4 by type 1 LSA, assuming that this type 1 LSA will be forwarded by the ABR R2 as a type 3 LSA to other areas, so other areas will know about R6, so there will be no need for Type 4 LSA as a helper for this redistributed type 5 LSA !!

[@PracticalNetworking]

>> assuming that this type 1 LSA will be forwarded by the ABR R2 as a type 3 LSA This isn't entirely correct. The actual Type 1 LSA will not be forwarded. Instead, only specific information from _within_ the Type 1 LSA is forwarded -- specifically _only the IP Subnets contained in the Type 1 LSA are forwarded._ The Routers identity (which is included in Type 1 LSAs) is not included in the Type 3 LSAs. To really understand it, I'd recommend the LSA Deep DIve videos: Type 1 & 2: kzbin.info/www/bejne/Z3eyc55_pKmVecU Type 3: kzbin.info/www/bejne/bpeppYhrjJ6Kfc0

[@guganobre]

Thanks for both contributions. I'd like to make a remark about LSA type 5 that originates from an external non-OSPF domain in an NSSA area. Shouldn't it be converted from type 7 to type 5?

[@ramend489]

4